Additive manufacturing system and method

ABSTRACT

An additive manufacturing system including a two-dimensional energy patterning system for imaging a powder bed is disclosed. Improved structure formation, part creation and manipulation, use of multiple additive manufacturing systems, and high throughput manufacturing methods suitable for automated or semi-automated factories are also disclosed.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

-   The present disclosure is part of a divisional of U.S. Pat. No.    15,336,505, filed on Oct. 27, 2016 and claiming the priority benefit    of the provisional applications listed below.-   U.S. Patent Application No. 62/248,758, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,765, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,770, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,776, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,783, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,791, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,799, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,966, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,968, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,969, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,980, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,989, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,780, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,787, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,795, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,821, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,829, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,833, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,835, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,839, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,841, filed on Oct. 30, 2015,-   U.S. Patent Application No. 62/248,847, filed on Oct. 30, 2015, and-   U.S. Patent Application No. 62/248,848, filed on Oct. 30, 2015,    which are incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to a system and method foradditive manufacturing. In one embodiment powder bed fusionmanufacturing with two-dimensional energy patterning and energy beamreuse are described.

BACKGROUND

Traditional component machining often relies on removal of material bydrilling, cutting, or grinding to form a part. In contrast, additivemanufacturing, also referred to as 3D printing, typically involvessequential layer by layer addition of material to build a part.Beginning with a 3D computer model, an additive manufacturing system canbe used to create complex parts from a wide variety of materials.

One additive manufacturing technique known as powder bed fusion (PBF)uses one or more focused energy sources, such as a laser or electronbeam, to draw a pattern in a thin layer of powder by melting the powderand bonding it to the layer below. Powders can be plastic, metal orceramic. This technique is highly accurate and can typically achievefeature sizes as small as 150-300 um. However, powder bed fusionadditive manufacturing machine manufacturers struggle to create machinesthat can produce printed material in excess of 1 kg/hr. Because of thisslow powder-to-solid conversion rate, machine sizes are relatively smalldue to the length of time it would take to print larger parts. Today'slargest machines have printable part volumes generally less than 64 L(40 cm)³. While these printers are capable of printing parts of nearlyarbitrary geometry, due to the high machine cost and low powderconversion rate the amortized cost of the machine ends up being veryhigh, resulting in expensive parts.

Unfortunately, increasing part size or decreasing manufacturing costs bysimply scaling-up the machine is not an acceptable solution. As aminimum, to melt a given volume of material the laser must deliver bothenough energy to bring it up to the melting temperature, and the phasechange energy required to melt. If no thermal energy is dissipated inthis process, then there is a linear scaling between laser energydeposited over time (laser power), and material throughput rate. If apowder bed fusion additive manufacturing machine maker wants to scale upin material throughput rate they would necessarily need to increasetheir laser power. This increase in laser power unfortunately increasesproportionally with the cost of the laser, and a scale up greatlyincreases the cost of today's already expensive machines.

Even if laser costs were not a factor, power scaling a laser can haveother detrimental effects. Every powdered material has optimum meltingproperties dependent on power flux. If power is too low, the powderdoesn't melt, and if too high the laser can drill into the material(key-holing). Increasing the laser power of a machine already operatingat one of these optimum points results necessarily requires an increasein laser area (spot size) to maintain the optimum power flux. Simplyincreasing the spot size degrades printable resolution, while dividingup the laser into multiple beams increases the system complexity.

In effect, currently available powder bed additive manufacturingmachines can be limited in part size, part manufacturing cost,resolution of part details, and part manufacturing throughput.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present disclosureare described with reference to the following figures, wherein likereference numerals refer to like parts throughout the various figuresunless otherwise specified.

FIG. 1A illustrates an additive manufacturing system;

FIG. 1B is a top view of a structure being formed on an additivemanufacturing system;

FIG. 2 illustrates an additive manufacturing method;

FIG. 3A is a cartoon illustrating an additive manufacturing systemincluding lasers;

FIG. 3B is a detailed description of the light patterning unit shown inFIG. 3A;

FIG. 3C is one embodiment of an additive manufacturing system with a“switchyard” for directing and patterning light using multiple imagerelays;

FIG. 3D illustrates a simple mirror image pixel remapping;

FIG. 3E illustrates a series of image transforming image relays forpixel remapping; and

FIG. 3F illustrates an patternable electron energy beam additivemanufacturing system;

FIG. 3G illustrates a detailed description of the electron beampatterning unit shown in FIG. 3F

FIG. 4A-C illustrate various beam combining embodiments;

FIGS. 5A-B illustrate reflective light patterning unit embodiments;

FIG. 6 illustrates light recycling;

FIG. 7 is a polarized beam system;

FIG. 8 is a flow chart for magnification changes and gantry movement;

FIGS. 9A-B respectively illustrate a powder bed system and a thermalmanagement system;

FIG. 10 is a flow chart illustrating additive formation of temporarywalls to contain powder;

FIGS. 11A-B illustrate embodiments for powder removal;

FIGS. 12A-B illustrate long part manufacture with multiple zones;

FIGS. 13A-C illustrate handling of a part at a manipulation point;

FIG. 14 is a representative part having additively defined manipulationpoints;

FIG. 15 is a flow chart illustrating powder sample testing andcharacterization;

FIG. 16 is an illustration of an enclosed additive manufacturingfacility;

FIG. 17 is an illustration of an additive manufacturing facility havingmultiple work areas

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings that form a part thereof, and in which is shown by way ofillustrating specific exemplary embodiments in which the disclosure maybe practiced. These embodiments are described in sufficient detail toenable those skilled in the art to practice the concepts disclosedherein, and it is to be understood that modifications to the variousdisclosed embodiments may be made, and other embodiments may beutilized, without departing from the scope of the present disclosure.The following detailed description is, therefore, not to be taken in alimiting sense.

An additive manufacturing system which has one or more energy sources,including in one embodiment, one or more laser or electron beams, arepositioned to emit one or more energy beams. Beam shaping optics mayreceive the one or more energy beams from the energy source and form asingle beam. An energy patterning unit receives or generates the singlebeam and transfers a two-dimensional pattern to the beam, and may rejectthe unused energy not in the pattern. An image relay receives thetwo-dimensional patterned beam and focuses it as a two-dimensional imageto a desired location on a height fixed or movable build platform (e.g.a powder bed). In certain embodiments, some or all of any rejectedenergy from the energy patterning unit is reused.

In some embodiments, multiple beams from the laser array(s) are combinedusing a beam homogenizer. This combined beam can be directed at anenergy patterning unit that includes either a transmissive or reflectivepixel addressable light valve. In one embodiment, the pixel addressablelight valve includes both a liquid crystal module having a polarizingelement and a light projection unit providing a two-dimensional inputpattern. The two-dimensional image focused by the image relay can besequentially directed toward multiple locations on a powder bed to builda 3D structure.

As seen in FIG. 1 , an additive manufacturing system 100 has an energypatterning system 110 with an energy source 112 that can direct one ormore continuous or intermittent energy beam(s) toward beam shapingoptics 114. After shaping, if necessary, the beam is patterned by anenergy patterning unit 116, with generally some energy being directed toa rejected energy handling unit 118. Patterned energy is relayed byimage relay 120 toward an article processing unit 140, typically as atwo-dimensional image 122 focused near a bed 146. The bed 146 (withoptional walls 148) can form a chamber containing material 144 dispensedby material dispenser 142. Patterned energy, directed by the image relay120, can melt, fuse, sinter, amalgamate, change crystal structure,influence stress patterns, or otherwise chemically or physically modifythe dispensed material 144 to form structures with desired properties.

Energy source 112 generates photon (light), electron, ion, or othersuitable energy beams or fluxes capable of being directed, shaped, andpatterned. Multiple energy sources can be used in combination. Theenergy source 112 can include lasers, incandescent light, concentratedsolar, other light sources, electron beams, or ion beams. Possible lasertypes include, but are not limited to: Gas Lasers, Chemical Lasers, DyeLasers, Metal Vapor Lasers, Solid State Lasers (e.g. fiber),Semiconductor (e.g. diode) Lasers, Free electron laser, Gas dynamiclaser, “Nickel-like” Samarium laser, Raman laser, or Nuclear pumpedlaser.

A Gas Laser can include lasers such as a Helium-neon laser, Argon laser,Krypton laser, Xenon ion laser, Nitrogen laser, Carbon dioxide laser,Carbon monoxide laser or Excimer laser.

A Chemical laser can include lasers such as a Hydrogen fluoride laser,Deuterium fluoride laser, COIL (Chemical oxygen-iodine laser), or Agil(All gas-phase iodine laser).

A Metal Vapor Laser can include lasers such as a Helium-cadmium (HeCd)metal-vapor laser, Helium-mercury (HeHg) metal-vapor laser,Helium-selenium (HeSe) metal-vapor laser, Helium-silver (HeAg)metal-vapor laser, Strontium Vapor Laser, Neon-copper (NeCu) metal-vaporlaser, Copper vapor laser, Gold vapor laser, or Manganese (Mn/MnCl₂)vapor laser.

A Solid State Laser can include lasers such as a Ruby laser, Nd:YAGlaser, NdCrYAG laser, Er:YAG laser, Neodymium YLF (Nd:YLF) solid-statelaser, Neodymium doped Yttrium orthovanadate (Nd:YVO₄) laser, Neodymiumdoped yttrium calcium oxoborateNd:YCa₄O(BO₃)³ or simply Nd:YCOB,Neodymium glass (Nd:Glass) laser, Titanium sapphire (Ti:sapphire) laser,Thulium YAG (Tm:YAG) laser, Ytterbium YAG (Yb:YAG) laser, Ytterbium:2O₃(glass or ceramics) laser, Ytterbium doped glass laser (rod, plate/chip,and fiber), Holmium YAG (Ho:YAG) laser, Chromium ZnSe (Cr:ZnSe) laser,Cerium doped lithium strontium (or calcium)aluminum fluoride (Ce:LiSAF,Ce:LiCAF), Promethium 147 doped phosphate glass (147Pm⁺³:Glass)solid-state laser, Chromium doped chrysoberyl (alexandrite) laser,Erbium doped anderbium-ytterbium co-doped glass lasers, Trivalenturanium doped calcium fluoride (U:CaF₂) solid-state laser, Divalentsamarium doped calcium fluoride (Sm:CaF₂) laser, or F-Center laser.

A Semiconductor Laser can include laser medium types such as GaN, InGaN,AlGaInP, AlGaAs, InGaAsP, GaInP, InGaAs, InGaAsO, GaInAsSb, lead salt,Vertical cavity surface emitting laser (VCSEL), Quantum cascade laser,Hybrid silicon laser, or combinations thereof.

For example, in one embodiment a single Nd:YAG q-switched laser can beused in conjunction with multiple semiconductor lasers. In anotherembodiment, an electron beam can be used in conjunction with anultraviolet semiconductor laser array. In still other embodiments, atwo-dimensional array of lasers can be used. In some embodiments withmultiple energy sources, pre-patterning of an energy beam can be done byselectively activating and deactivating energy sources.

Beam shaping unit 114 can include a great variety of imaging optics tocombine, focus, diverge, reflect, refract, homogenize, adjust intensity,adjust frequency, or otherwise shape and direct one or more energy beamsreceived from the energy source 112 toward the energy patterning unit116. In one embodiment, multiple light beams, each having a distinctlight wavelength, can be combined using wavelength selective mirrors(e.g. dichroics) or diffractive elements. In other embodiments, multiplebeams can be homogenized or combined using multifaceted mirrors,microlenses, and refractive or diffractive optical elements.

Energy patterning unit 116 can include static or dynamic energypatterning elements. For example, photon, electron, or ion beams can beblocked by masks with fixed or movable elements. To increase flexibilityand ease of image patterning, pixel addressable masking, imagegeneration, or transmission can be used. In some embodiments, the energypatterning unit includes addressable light valves, alone or inconjunction with other patterning mechanisms to provide patterning. Thelight valves can be transmissive, reflective, or use a combination oftransmissive and reflective elements. Patterns can be dynamicallymodified using electrical or optical addressing. In one embodiment, atransmissive optically addressed light valve acts to rotate polarizationof light passing through the valve, with optically addressed pixelsforming patterns defined by a light projection source. In anotherembodiment, a reflective optically addressed light valve includes awrite beam for modifying polarization of a read beam. In yet anotherembodiment, an electron patterning device receives an address patternfrom an electrical or photon stimulation source and generates apatterned emission of electrons.

Rejected energy handling unit 118 is used to disperse, redirect, orutilize energy not patterned and passed through the energy pattern imagerelay 120. In one embodiment, the rejected energy handling unit 118 caninclude passive or active cooling elements that remove heat from theenergy patterning unit 116. In other embodiments, the rejected energyhandling unit can include a “beam dump” to absorb and convert to heatany beam energy not used in defining the energy pattern. In still otherembodiments, rejected beam energy can be recycled using beam shapingoptics 114. Alternatively, or in addition, rejected beam energy can bedirected to the article processing unit 140 for heating or furtherpatterning. In certain embodiments, rejected beam energy can be directedto additional energy patterning systems or article processing units.

Image relay 120 receives a patterned image (typically two-dimensional)from the energy patterning unit 116 and guides it toward the articleprocessing unit 140. In a manner similar to beam shaping optics 114, theimage relay 120 can include optics to combine, focus, diverge, reflect,refract, adjust intensity, adjust frequency, or otherwise shape anddirect the patterned image.

Article processing unit 140 can include a walled chamber 148 and bed144, and a material dispenser 142 for distributing material. Thematerial dispenser 142 can distribute, remove, mix, provide gradationsor changes in material type or particle size, or adjust layer thicknessof material. The material can include metal, ceramic, glass, polymericpowders, other melt-able material capable of undergoing a thermallyinduced phase change from solid to liquid and back again, orcombinations thereof. The material can further include composites ofmelt-able material and non-melt-able material where either or bothcomponents can be selectively targeted by the imaging relay system tomelt the component that is melt-able, while either leaving along thenon-melt-able material or causing it to undergo avaporizing/destroying/combusting or otherwise destructive process. Incertain embodiments, slurries, sprays, coatings, wires, strips, orsheets of materials can be used. Unwanted material can be removed fordisposable or recycling by use of blowers, vacuum systems, sweeping,vibrating, shaking, tipping, or inversion of the bed 146.

In addition to material handling components, the article processing unit140 can include components for holding and supporting 3D structures,mechanisms for heating or cooling the chamber, auxiliary or supportingoptics, and sensors and control mechanisms for monitoring or adjustingmaterial or environmental conditions. The article processing unit can,in whole or in part, support a vacuum or inert gas atmosphere to reduceunwanted chemical interactions as well as to mitigate the risks of fireor explosion (especially with reactive metals).

Control processor 150 can be connected to control any components ofadditive manufacturing system 100. The control processor 150 can beconnected to variety of sensors, actuators, heating or cooling systems,monitors, and controllers to coordinate operation. A wide range ofsensors, including imagers, light intensity monitors, thermal, pressure,or gas sensors can be used to provide information used in control ormonitoring. The control processor can be a single central controller, oralternatively, can include one or more independent control systems. Thecontroller processor 150 is provided with an interface to allow input ofmanufacturing instructions. Use of a wide range of sensors allowsvarious feedback control mechanisms that improve quality, manufacturingthroughput, and energy efficiency.

FIG. 1B is a cartoon illustrating a bed 146 that supports material 144.Using a series of sequentially applied, two-dimensional patterned energybeam images (squares in dotted outline 124), a structure 149 isadditively manufactured. As will be understood, image patterns havingnon-square boundaries can be used, overlapping or interpenetratingimages can be used, and images can be provided by two or more energypatterning systems. In other embodiments, images can be formed inconjunction with directed electron or ion beams, or with printed orselective spray systems.

FIG. 2 is a flow chart illustrating one embodiment of an additivemanufacturing process supported by the described optical and mechanicalcomponents. In step 202, material is positioned in a bed, chamber, orother suitable support. The material can be a powder capable of beingmelted, fused, sintered, induced to change crystal structure, havestress patterns influenced, or otherwise chemically or physicallymodified to form structures with desired properties.

In step 204, unpatterned energy is emitted by one or more energyemitters, including but not limited to solid state or semiconductorlasers, or electrical power supply flowing electrons down a wire. Instep 206, the unpatterned energy is shaped and modified (e.g. intensitymodulated or focused). In step 208, this unpatterned energy ispatterned, with energy not forming a part of the pattern being handledin step 210 (this can include conversion to waste heat, or recycling aspatterned or unpatterned energy). In step 212, the patterned energy, nowforming a two-dimensional image is relayed toward the material. In step214, the image is applied to the material, building a portion of a 3Dstructure. These steps can be repeated (loop 218) until the image (ordifferent and subsequent image) has been applied to all necessaryregions of a top layer of the material. When application of energy tothe top layer of the material is finished, a new layer can be applied(loop 216) to continue building the 3D structure. These process loopsare continued until the 3D structure is complete, when remaining excessmaterial can be removed or recycled.

FIG. 3A is one embodiment of an additive manufacturing system 300 thatuses multiple semiconductor lasers as part of an energy patterningsystem 310. A control processor 350 can be connected to variety ofsensors, actuators, heating or cooling systems, monitors, andcontrollers to coordinate operation of multiple lasers 312, lightpatterning unit 316, and image relay 320, as well as any other componentof system 300. These connections are generally indicated by a dottedoutline 351 surrounding components of system 300. As will beappreciated, connections can be wired or wireless, continuous orintermittent, and include capability for feedback (for example, thermalheating can be adjusted in response to sensed temperature). The multiplelasers 312 can emit a beam 301 of light at a 1000 nm wavelength that,for example, is 90 mm wide by 20 mm tall. The beam 301 is resized byimaging optics 370 to create beam 303. Beam 303 is 6 mm wide by 6 mmtall, and is incident on light homogenization device 372 which blendslight together to create blended beam 305. Beam 305 is then incident onimaging assembly 374 which reshapes the light into beam 307 and is thenincident on hot cold mirror 376. The mirror 376 allows 1000 nm light topass, but reflects 450 nm light. A light projector 378 capable ofprojecting low power light at 1080p pixel resolution and 450 nm emitsbeam 309, which is then incident on hot cold mirror 376. Beams 307 and309 overlay in beam 311, and both are imaged onto optically addressedlight valve 380 in a 20 mm wide, 20 mm tall image. Images formed fromthe homogenizer 372 and the projector 378 are recreated and overlaid onlight valve 380.

The optically addressed light valve 380 is stimulated by the light(typically ranging from 400-500 nm) and imprints a polarization rotationpattern in transmitted beam 313 which is incident upon polarizer 382.The polarizer 382 splits the two polarization states, transmittingp-polarization into beam 317 and reflecting s-polarization into beam 315which is then sent to a beam dump 318 that handles the rejected energy.As will be understood, in other embodiments the polarization could bereversed, with s-polarization formed into beam 317 and reflectingp-polarization into beam 315. Beam 317 enters the final imaging assembly320 which includes optics 384 that resize the patterned light. This beamreflects off of a movable mirror 386 to beam 319, which terminates in afocused image applied to material bed 344 in an article processing unit340. The depth of field in the image selected to span multiple layers,providing optimum focus in the range of a few layers of error or offset.

The bed 390 can be raised or lowered (vertically indexed) within chamberwalls 388 that contain material 344 dispensed by material dispenser 342.In certain embodiments, the bed 390 can remain fixed, and optics of thefinal imaging assembly 320 can be vertically raised or lowered. Materialdistribution is provided by a sweeper mechanism 392 that can evenlyspread powder held in hopper 394, being able to provide new layers ofmaterial as needed. An image 6 mm wide by 6 mm tall can be sequentiallydirected by the movable mirror 386 at different positions of the bed.

When using a powdered ceramic or metal material in this additivemanufacturing system 300, the powder can be spread in a thin layer,approximately 1-3 particles thick, on top of a base substrate (andsubsequent layers) as the part is built. When the powder is melted,sintered, or fused by a patterned beam 319, it bonds to the underlyinglayer, creating a solid structure. The patterned beam 319 can beoperated in a pulsed fashion at 40 Hz, moving to the subsequent 6 mm×6mm image locations at intervals of 10 ms to 0.5 ms (with 3 to 0.1 msbeing desirable) until the selected patterned areas of powder have beenmelted. The bed 390 then lowers itself by a thickness corresponding toone layer, and the sweeper mechanism 392 spreads a new layer of powderedmaterial. This process is repeated until the 2D layers have built up thedesired 3D structure. In certain embodiments, the article processingunit 340 can have a controlled atmosphere. This allows reactivematerials to be manufactured in an inert gas, or vacuum environmentwithout the risk of oxidation or chemical reaction, or fire or explosion(if reactive metals are used).

FIG. 3B illustrates in more detail operation of the light patterningunit 316 of FIG. 3A. As seen in FIG. 3B, a representative input pattern333 (here seen as the numeral “9”) is defined in an 8×12 pixel array oflight projected as beam 309 toward mirror 376. Each grey pixelrepresents a light filled pixel, while white pixels are unlit. Inpractice, each pixel can have varying levels of light, includinglight-free, partial light intensity, or maximal light intensity.Unpatterned light 331 that forms beam 307 is directed and passes througha hot/cold mirror 376, where it combines with patterned beam 309. Afterreflection by the hot/cold mirror 376, the patterned light beam 311formed from overlay of beams 307 and 309 in beam 311, and both areimaged onto optically addressed light valve 380. The optically addressedlight valve 380, which would rotate the polarization state ofunpatterned light 331, is stimulated by the patterned light beam 309,311 to selectively not rotate the polarization state of polarized light307, 311 in the pattern of the numeral “9” into beam 313. The unrotatedlight representative of pattern 333 in beam 313 is then allowed to passthrough polarizer mirror 382 resulting in beam 317 and pattern 335.Polarized light in a second rotated state is rejected by polarizermirror 382, into beam 315 carrying the negative pixel pattern 337consisting of a light-free numeral “9”.

Other types of light valves can be substituted or used in combinationwith the described light valve. Reflective light valves, or light valvesbase on selective diffraction or refraction can also be used. In certainembodiments, non-optically addressed light valves can be used. These caninclude but are not limited to electrically addressable pixel elements,movable mirror or micro-mirror systems, piezo or micro-actuated opticalsystems, fixed or movable masks, or shields, or any other conventionalsystem able to provide high intensity light patterning. For electronbeam patterning, these valves may selectively emit electrons based on anaddress location, thus imbuing a pattern on the beam of electronsleaving the valve.

FIG. 3C is one embodiment of an additive manufacturing system thatincludes a switchyard system enabling reuse of patterned two-dimensionalenergy. Similar to the embodiment discussed with respect to FIG. 1A, anadditive manufacturing system 220 has an energy patterning system withan energy source 112 that directs one or more continuous or intermittentenergy beam(s) toward beam shaping optics 114. After shaping, the beamis two-dimensionally patterned by an energy patterning unit 230, withgenerally some energy being directed to a rejected energy handling unit222. Patterned energy is relayed by one of multiple image relays 232toward one or more article processing units 234A, 234B, 234C, or 234D,typically as a two-dimensional image focused near a movable or fixedheight bed. The bed (with optional walls) can form a chamber containingmaterial dispensed by material dispenser. Patterned energy, directed bythe image relays 232, can melt, fuse, sinter, amalgamate, change crystalstructure, influence stress patterns, or otherwise chemically orphysically modify the dispensed material to form structures with desiredproperties.

In this embodiment, the rejected energy handling unit has multiplecomponents to permit reuse of rejected patterned energy. Relays 228A,228B, and 22C can respectively transfer energy to an electricitygenerator 224, a heat/cool thermal management system 225, or an energydump 226. Optionally, relay 228C can direct patterned energy into theimage relay 232 for further processing. In other embodiments, patternedenergy can be directed by relay 228C, to relay 228B and 228A forinsertion into the energy beam(s) provided by energy source 112. Reuseof patterned images is also possible using image relay 232. Images canbe redirected, inverted, mirrored, sub-patterned, or otherwisetransformed for distribution to one or more article processing units.234A-D. Advantageously, reuse of the patterned light can improve energyefficiency of the additive manufacturing process, and in some casesimprove energy intensity directed at a bed, or reduce manufacture time.

FIG. 3D is a cartoon 235 illustrating a simple geometricaltransformation of a rejected energy beam for reuse. An input pattern 236is directed into an image relay 237 capable of providing a mirror imagepixel pattern 238. As will be appreciated, more complex pixeltransformations are possible, including geometrical transformations, orpattern remapping of individual pixels and groups of pixels. Instead ofbeing wasted in a beam dump, this remapped pattern can be directed to anarticle processing unit to improve manufacturing throughput or beamintensity.

FIG. 3E is a cartoon 235 illustrating multiple transformations of arejected energy beam for reuse. An input pattern 236 is directed into aseries of image relays 237B-E capable of providing a pixel pattern 238.

FIGS. 3F and 3G illustrates a non-light based energy beam system 240that includes a patterned electron beam 241 capable of producing, forexample, a “P” shaped pixel image. A high voltage electricity powersystem 243 is connected to an optically addressable patterned cathodeunit 245. In response to application of a two-dimensional patternedimage by projector 244, the cathode unit 245 is stimulated to emitelectrons wherever the patterned image is optically addressed. Focusingof the electron beam pattern is provided by an image relay system 247that includes imaging coils 246A and 246B. Final positioning of thepatterned image is provided by a deflection coil 248 that is able tomove the patterned image to a desired position on a bed of additivemanufacturing component 249.

In another embodiment supporting light recycling and reuse, multiplexmultiple beams of light from one or more light sources are provided. Themultiple beams of light may be reshaped and blended to provide a firstbeam of light. A spatial polarization pattern may be applied on thefirst beam of light to provide a second beam of light. Polarizationstates of the second beam of light may be split to reflect a third beamof light, which may be reshaped into a fourth beam of light. The fourthbeam of light may be introduced as one of the multiple beams of light toresult in a fifth beam of light. In effect, this or similar systems canreduce energy costs associated with an additive manufacturing system. Bycollecting, beam combining, homogenizing and re-introducing unwantedlight rejected by a spatial polarization valve or light valve operatingin polarization modification mode, overall transmitted light power canpotentially be unaffected by the pattern applied by a light valve. Thisadvantageously results in an effective re-distribution of the lightpassing through the light valve into the desired pattern, increasing thelight intensity proportional to the amount of area patterned.

Combining beams from multiple lasers into a single beam is one way toincreasing beam intensity. In one embodiment, multiple light beams, eachhaving a distinct light wavelength, can be combined using eitherwavelength selective mirrors or diffractive elements. In certainembodiments, reflective optical elements that are not sensitive towavelength dependent refractive effects can be used to guide amultiwavelength beam.

Patterned light can be directed using movable mirrors, prisms,diffractive optical elements, or solid state optical systems that do notrequire substantial physical movement. In one embodiment, amagnification ratio and an image distance associated with an intensityand a pixel size of an incident light on a location of a top surface ofa powder bed can be determined for an additively manufactured,three-dimensional (3D) print job. One of a plurality of lens assembliescan be configured to provide the incident light having the magnificationratio, with the lens assemblies both a first set of optical lenses and asecond sets of optical lenses, and with the second sets of opticallenses being swappable from the lens assemblies. Rotations of one ormore sets of mirrors mounted on compensating gantries and a final mirrormounted on a build platform gantry can be used to direct the incidentlight from a precursor mirror onto the location of the top surface ofthe powder bed. Translational movements of compensating gantries and thebuild platform gantry are also able to ensure that distance of theincident light from the precursor mirror to the location of the topsurface of the powder bed is substantially equivalent to the imagedistance. In effect, this enables a quick change in the optical beamdelivery size and intensity across locations of a build area fordifferent powdered materials while ensuring high availability of thesystem.

In certain embodiments, a plurality of build chambers, each having abuild platform to hold a powder bed, can be used in conjunction withmultiple optical-mechanical assemblies arranged to receive and directthe one or more incident energy beams into the build chambers. Multiplechambers allow for concurrent printing of one or more print jobs insideone or more build chambers. In other embodiments, a removable chambersidewall can simplify removal of printed objects from build chambers,allowing quick exchanges of powdered materials. The chamber can also beequipped with an adjustable process temperature controls.

In another embodiment, one or more build chambers can have a buildchamber that is maintained at a fixed height, while optics arevertically movable. A distance between final optics of a lens assemblyand a top surface of powder bed a may be managed to be essentiallyconstant by indexing final optics upwards, by a distance equivalent to athickness of a powder layer, while keeping the build platform at a fixedheight. Advantageously, as compared to a vertically moving the buildplatform, large and heavy objects can be more easily manufactured, sinceprecise micron scale movements of the build platform are not needed.Typically, build chambers intended for metal powders with a volume morethan ˜0.1-0.2 cubic meters (i.e., greater than 100-200 liters or heavierthan 500-1,000 kg) will most benefit from keeping the build platform ata fixed height.

In one embodiment, a portion of the layer of the powder bed may beselectively melted or fused to form one or more temporary walls out ofthe fused portion of the layer of the powder bed to contain anotherportion of the layer of the powder bed on the build platform. Inselected embodiments, a fluid passageway can be formed in the one ormore first walls to enable improved thermal management.

Improved powder handling can be another aspect of an improved additivemanufacturing system. A build platform supporting a powder bed can becapable of tilting, inverting, and shaking to separate the powder bedsubstantially from the build platform in a hopper. The powdered materialforming the powder bed may be collected in a hopper for reuse in laterprint jobs. The powder collecting process may be automated, andvacuuming or gas jet systems also used to aid powder dislodgement andremoval

Some embodiments of the disclosed additive manufacturing system can beconfigured to easily handle parts longer than an available chamber. Acontinuous (long) part can be sequentially advanced in a longitudinaldirection from a first zone to a second zone. In the first zone,selected granules of a granular material can be amalgamated. In thesecond zone, unamalgamated granules of the granular material can beremoved. The first portion of the continuous part can be advanced fromthe second zone to a third zone, while a last portion of the continuouspart is formed within the first zone and the first portion is maintainedin the same position in the lateral and transverse directions that thefirst portion occupied within the first zone and the second zone. Ineffect, additive manufacture and clean-up (e.g., separation and/orreclamation of unused or unamalgamated granular material) may beperformed in parallel (i.e., at the same time) at different locations orzones on a part conveyor, with no need to stop for removal of granularmaterial and/or parts.

In another embodiment, additive manufacturing capability can be improvedby use of an enclosure restricting an exchange of gaseous matter betweenan interior of the enclosure and an exterior of the enclosure. Anairlock provides an interface between the interior and the exterior;with the interior having multiple additive manufacturing chambers,including those supporting power bed fusion. A gas management systemmaintains gaseous oxygen within the interior at or below a limitingoxygen concentration, increasing flexibility in types of powder andprocessing that can be used in the system.

In another manufacturing embodiment, capability can be improved byhaving a 3D printer contained within an enclosure, the printer able tocreate a part having a weight greater than or equal to 2,000 kilograms.A gas management system may maintain gaseous oxygen within the enclosureat concentrations below the atmospheric level. In some embodiments, awheeled vehicle may transport the part from inside the enclosure,through an airlock, since the airlock operates to buffer between agaseous environment within the enclosure and a gaseous environmentoutside the enclosure, and to a location exterior to both the enclosureand the airlock.

Other manufacturing embodiments involve collecting powder samples inreal-time in a powder bed fusion additive manufacturing system. Aningester system is used for in-process collection and characterizationsof powder samples. The collection may be performed periodically and theresults of characterizations result in adjustments to the powder bedfusion process. The ingester system can optionally be used for one ormore of audit, process adjustments or actions such as modifying printerparameters or verifying proper use of licensed powder materials.

Yet another improvement to an additive manufacturing process can beprovided by use of a manipulator device such as a crane, lifting gantry,robot arm, or similar that allows for the manipulation of parts thatwould be difficult or impossible for a human to move is described. Themanipulator device can grasp various permanent or temporary additivelymanufactured manipulation points on a part to enable repositioning ormaneuvering of the part.

FIG. 4A illustrates a beam combining system 400 having multiplewavelength semiconductor lasers and using transmissive imaging optics.As will be understood, the discussed laser powers and wavelengths areexemplary, as are the selected wavelengths reflected or transmitted bywavelength filters. With the appropriate changes in positioning and useof wavelength filters, greater or lesser numbers of lasers can be used.In certain embodiments, solid state lasers can be substituted or used incombination with semiconductor lasers. In other embodiments, other lasertypes such as discussed with respect to FIG. 1 , including gas,chemical, or metal vapor lasers can be used. In one embodiment,recycling and reuse of rejected light can substitute for a laser.Rejected light available in an additive manufacturing system can becollected, homogenized and re-introduced into a beam line.Advantageously, recycling and re-using rejected light can increase beamintensity and reduce energy costs associated with the system.

In FIG. 4A, semiconductor lasers of a first wavelength (1020 nm) 406emit a 33.3 kW beam of photons of a corresponding wavelength 407,semiconductor lasers of a second wavelength (1000 nm) 408 emit a 33.3 kWbeam of photons of the corresponding wavelength 409, which are thencombined using a wavelength filter 410 that transmits 1020 nm photons,but reflects 1000 nm photons. This results in a combined two-wavelengthbeam 411 of 66.6 kW. Semiconductor lasers of a third wavelength (980 nm)412 emit a 33.3 kW beam of photons of the corresponding wavelength 413which are then combined with beam 411 using a wavelength filter 414.Wavelength filter 414 transmits 1020 and 1000 nm, but reflects the 980nm beam, resulting in a three-wavelength beam 415 of 99.9 kW.Semiconductor lasers of a fourth wavelength (960 nm) 417 emit a 33.3 kWbeam of photons of the corresponding wavelength 418 which are thencombined with beam 415 using a wavelength filter 416 that transmits 1020nm, 1000 nm, and 980 nm photons, but reflects 960 nm, resulting in afour-wavelength beam 419 of 133.2 kW. This beam enters the opticalimaging system with beam dimensions, for example, of 20 mm×20 mm and adivergence of 1.1 degrees at lenses 420. Lenses 420 are a series oflenses that use two materials, C79-79 and ULE 7972, each having adifferent index of refraction, to cancel out the effect of wavelengthvariance on the ability to image the beam. The beam exits the opticalsystem at 421, which is a series of lenses that utilizes threematerials, ZeruDur, ULE 7972, and C79-79 to cancel out the effect ofwavelength variance on the ability to image the beam. The beam at 422has been increased in intensity as a result of passing through theoptical system and is now 6 mm wide×6 mm tall at 3.67 degrees ofdivergence resulting in an intensity of 370 kW/cm², sufficient for theadditive manufacturing processing of metals such as powdered stainlesssteel.

Proper selection of lens material is necessary for best performance.Transmissive optics such as lenses 420 can be made with fused silicaglass. This reduces thermal expansion problems due to extremely lowcoefficients of absorption at wavelengths near 1000 nm, and reducesthermal expansion of lenses due to the extremely low coefficients ofthermal expansion fused silica. The use of fused silica allows for theoptics to withstand much higher intensities without heating up andexpanding which can lead to fracture, changes in the glass index ofrefraction, changes in glass shape, and consequent changes in focalpoints. Unwanted optical changes can also be reduced by use of two ormore materials. Each material can have a different index of refractionwhich changes differently with wavelength. Used in the appropriatecombination, the changes in index and optical path length cancel out,and there no variance in focal distance as a function of wavelength.

FIG. 4B illustrates an alternative beam combining system 401 thatincludes a combination of multiple wavelength semiconductor lasers anduses reflective imaging optics to reduce the foregoing discussed issuesassociated with transmissive optics. Like the beam combining system 400of FIG. 4A, it will be understood, the discussed laser powers andwavelengths in system 401 are exemplary, as are the selected wavelengthsreflected or transmitted by wavelength filters. With the appropriatechanges in positioning and use of wavelength filters, greater or lessernumbers of lasers can be used. Multiple types of lasers can be used, andin one embodiment, recycling and reuse of rejected light can substitutefor a laser. Rejected light available in an additive manufacturingsystem can be collected, homogenized and re-introduced into a beam line.Advantageously, reflective optics improve problems associated withsemiconductor laser chirp (shift of wavelength over time) during startuptransients and over their lifetime. The use of reflective opticsprevents detuning of diode laser focus due to this effect and does notaffect the resolution achieved or imaging capability. In addition, byusing reflective optics, wavelength differences caused by variation inlaser operating temperature do not affect the resolution or imagingcapability.

In FIG. 4B, semiconductor lasers of a first wavelength (1020 nm) 423emit a 33.3 kW beam of photons of the corresponding wavelength 424,semiconductor lasers of a second wavelength (1000 nm) 425 emit a 33.3 kWbeam of photons of the corresponding wavelength 426. These beams arecombined using a wavelength filter 427 that transmits 1020 nm photons,but reflects 1000 nm photons, resulting is a two-wavelength beam 428 of66.6 kW. Semiconductor lasers of a third wavelength (980 nm) 429 emit a33.3 kW beam of photons of the corresponding wavelength 430. These beamsare combined with beam 428 using a wavelength filter 431 which transmits1020 and 1000 nm, but reflects 980 nm, resulting in a three-wavelengthbeam 432 of 99.9 kW. Semiconductor lasers of a fourth wavelength (960nm) 433 emit a 33.3 kW beam of photons of the corresponding wavelength434. These beams are combined with beam 432 using a wavelength filter435 that transmits 1020 nm, 1000 nm, and 980 nm photons, but reflects960 nm, resulting in a four-wavelength beam 436 of 133.2 kW. This beamenters the optical imaging system with, for example, beam dimensions of20 mm×20 mm and a divergence of 1.1 degrees at reflective optic 437.Reflective optics have no dependence on wavelength and do not affect theability to image the beam. The beam exits the beam combining opticalsystem 401 at reflective optic 438. The beam 439 has been increased inintensity as a result of passing through the optical system and is now 6mm wide×6 mm tall at 3.67 degrees of divergence resulting in anintensity of 370 kW/cm², sufficient for the additive manufacturingprocessing of metals such as powdered stainless steel.

FIG. 4C illustrates an alternative embodiment of a beam combining system440 that combines beams 443 from same or multiple wavelength lasers 442using a diffractive imaging optic 444. The diffractive optic can beshaped or patterned to receive beams 443, and reflect them along asubstantially same beam axis. As will be understood, while a diffractiveoptic that reflects beams is shown in FIG. 4C, in other embodiments thediffractive optic can transmit beams, or use a combination ofreflective, transmissive, or other suitable beam steering opticalassemblies or components.

FIG. 5A is a reflective optically addressed light valve system 500Auseful in additive manufacturing systems such as disclosed herein.Reflective light valves do not need to transmit light through atransparent semiconductor for light patterning, where at high averagepower levels, even small amounts of absorption can cause unwanted andcatastrophic heating. Reflective light valves can also allow for agreater ease of cooling on the reflective surface, with cooling on anopposing side to where the write beam and the read beam are incident.

As seen in FIG. 5A, the reflective optically addressed light valvesystem 500A is capable of patterning an energy beam and is composed of ahighly transmissive layer 501, a twisted nematic (TN) liquid crystallayer 502, and a photoconductor layer 503. The highly transmissive layeris optically transparent for 1000 nm and 700 nm light, made from glasssubstrate (C79-79 fused silica) 501 which has anti-reflective coatingson both sides at 504 and 506. An Indium Tin Oxide (ITO) conductivecoating is applied to highly transmissive layer 501 at 505. Layer 502 isanchored to 506 and 510 by way of anchoring substrates 507 and 509. Theexact spacing of 502 is given by the size of the spacer balls 508 whichdefine a gap of 2.5 microns, tuned for maximum contrast ratio whenpassing 1000 nm light in a double pass. Layer 503 is made of a singlecrystalline silicon semiconductor with a high reflection dielectriccoating applied at 510 which is transparent to 700 nm, but reflective at1000 nm. Layer 511 is another layer of ITO which has a solder pointattached 512 and is connected to layer 505 by way of an AC voltagesource 514 by way of another solder point 513. A patterned write beam oflight is emitted from a projector source at 700 nm and is incident on503 after transmitting through 504, 501, 505, 506, 507, 502, 509 and510. Where the write beam strikes 503 electrons move from the valenceband to the conduction band, greatly increasing the local electricalconductivity of 503, allowing current to flow from 511 through 503, 510,509, 502, 507, and 506 to 505. As current flows through the TN liquidcrystal 502, it induces rotation in the liquid crystal 502 causingpolarization rotation in transmitted light. The “read” beam 516 isp-polarized and is incident on 510 after transmitting through 504, 501,505, 506, 507, 502, and 509 at which point it reflects and transmitsback through 509, 502, 507, 506, 505, 501, and 504 to exit the lightvalve system 500A. This beam is then incident on a polarizer 517 whichreflects s-polarization resulting in reflected beam 518 and transmitsp-polarization resulting in transmitted beam 519. Even though absorptionis very low in the device the HR coating 509 is not perfectly reflectingand some energy is absorbed. This energy is removed by radiative,conductive, or convective cooling 520.

FIG. 5B illustrates an alternative reflective optically addressed lightvalve 500B with cooling on one side where the write beam and the readbeam are incident from the different sides. The valve is composed of ahighly transmissive layer 521, a twisted nematic (TN) liquid crystallayer 522, and a photoconductor layer 523. The highly transmissive layeris optically transparent for 1000 nm and 700 nm light, made from glasssubstrate (C79-79 fused silica) 521 which has anti-reflective coatingson both sides at 524 and 526. An Indium Tin Oxide (ITO) conductivecoating is applied to 521 at 525. Layer 522 is anchored to 526 and 530by way of anchoring substrates 527 and 259. The exact spacing of 522 isgiven by the size of the spacer balls 528 which define a gap of 2.5microns, tuned for maximum contrast ratio when passing 1000 nm light ina double pass. Layer 523 is made of a single crystalline siliconsemiconductor with a high reflection dielectric coating applied at 530which reflective at 1000 nm. Layer 531 is another layer of ITO which hasa solder point attached 532 and is connected to layer 525 by way of anAC voltage source 534 by way of another solder point 533. A patternedwrite beam of light is emitted from a projector source at 700 nm and isincident on 523 after transmitting through a an optionalconvective/conductive substrate 540 and through the ITO coating 531.Where the write beam strikes 503 electrons move from the valence band tothe conduction band, greatly increasing the local electricalconductivity of 523, allowing current to flow from 531 through 523, 530,529, 522, 527, and 526 to 525. As current flows through the TN liquidcrystal 522, it induces rotation in the liquid crystal 522 causingpolarization rotation in transmitted light. The “read” beam 536 isp-polarized and is incident on 530 after transmitting through 524, 521,525, 526, 527, 522, and 529 at which point it reflects and transmitsback through 529, 522, 527, 526, 525, 521, and 524 to exit the lightvalve. This beam is then incident on a polarizer 537 which reflectss-polarization resulting in reflected beam 538 and transmitsp-polarization resulting in transmitted beam 539. Even though absorptionis very low in the device the HR coating 529 is not perfectly reflectingand some energy is absorbed. This energy is removed by radiative,conductive, or convective cooling 540.

To aid better understanding and appreciation of the various systemembodiments, including alternative or additional optical systems,chamber designs, powder handling systems and methods, structureformation, part creation and manipulation, use of multiple additivemanufacturing systems, and high throughput manufacturing methodssuitable for automated or semi-automated factories; the followingdisclosure will aid in understanding and appreciation of various novelaspects of the disclosed systems, methods, and structures.

FIG. 6 illustrates a layout of an example apparatus 400 for laser lightrecycling in the additive manufacturing process. Apparatus 600 mayinclude one or more light sources such as, for example and withoutlimitation, light sources 601, 602, and 603. In some embodiments, lightsources 601, 602, and 603 may include lasers. Alternatively, other typesof light sources such as solid state lasers may be utilized. In someembodiments, each or at least one of light sources 601, 602, and 603 mayemit 11.1 kW of p-polarized light at 700 nm, having a size of 7.9 cm×7.9cm, and 7.6 mrad in divergence. Beams of light emitted by light sources601, 602, and 603 may be multiplexed together by a first opticalassembly 604, which may include a series of mirrors, thus allowing thebeams to be as close together as possible. These beams are then reshapedand blended by an optical device 605, resulting in a beam 6, 33.3 kW,4.7 cm×4.7 cm and 70.4 mrad in divergence. Beam 606 may then be incidenton a spatial polarization valve 607, which can apply a spatialpolarization pattern map on beam 606 by rotating the polarization ofselected pixels from p-polarization to s-polarization to provide a beam8. With suitable modifications, the selected pixels can be formed byrotating from s-polarization to p-polarization to provide the beam. Instill other embodiments, grey scale pixels can be created by partialrotations. Upon interaction with a polarizer 609 the s-polarizationstate of beam 608 may be reflected into a beam 610. The exact fractionmay be given as a function of the fraction of light that is patterned bya spatial polarization valve 607. Beam 10 may enter a second opticalassembly 611, which may include a series of mirrors, re-shaping lenses,waveplates, or other optical components, and may be modified into a 7.9cm×7.9 cm beam and then re-introduced to the system as if it were alight source 612, along with the original one or more light sources 601,602, and 603.

A process for light recycling can include the steps of multiplexingmultiple beams of light including at least one or more beams of lightfrom one or more light sources 601, 602, and 603. The multiple beams oflight can be reshaped and blended to provide a first beam of light. Aspatial polarization valve 607 of apparatus 600 applies a spatialpolarization pattern on the first beam of light to provide a second beamof light. A polarizer 609 of apparatus 600 splits polarization states ofthe second beam of light 608 to reflect a third beam of light (e.g.,beam 610). A second optical assembly 611 of apparatus 600 reshapes thethird beam of light into a fourth beam of light, and the fourth beam oflight is introduced to first optical assembly 604 as one of the multiplebeams of light to result in a fifth beam of light (e.g., beam 613) thatis emitted through and not reflected by polarizer 609.

FIG. 7 illustrates an example optical assembly 700 of polarizationcombining to achieve up to 2× of the original semiconductor laserintensity (in the limit) in accordance with the present disclosure.Semiconductor lasers are typically polarized to about 70-90% in onepolarization state. When using a polarization rotating method to patternthe light, the 10-20% of the light in the undesired polarization statecould potentially go unused (rejected). To avoid this loss, polarizationcombining and patterning can be used to either boost transmissionefficiency or increase resultant intensity by a factor of 2, or both.

In one embodiment, two or more beams of light with a first intensity areprovided, each of the two or more beams of light being polarized andhaving a majority polarization state and a minority polarization state.A respective polarization pattern is applied on the majoritypolarization state of each of the two or more beams of light and the twoor more beams of light are combined to provide a single beam of lightwith a second intensity greater than the first intensity. In a secondembodiment, more than one laser of an arbitrary polarization state canbe used. A polarizer is used to split the beam(s) into its (their)respective polarization state(s), and spatially stack the beam(s) ofcorresponding polarization state(s) close together by spatialpositioning creating two effective beams, with one of each polarizationstate. These two beams, of different polarization state, are then passedthrough a light modulator relating to their perspective polarizationstate, then with a polarization state pattern applied in the beam, andsubsequently beam combined by polarization combining. This method usesall light in the process, which allows for higher usage of the laserlight, thereby achieving minimal to no losses, due to variance inpolarization state, as well as better system efficiency.

Optical assembly 700 may include some or all of those components shownin FIG. 7 , to be described as follows. Light sources 701 and 702 areeach used as a high power photon source. In some embodiments, lightsources 701 and 702 may be semiconductor laser arrays with 33.3 kW ofpower each, emitting photons at 1000 nm that are shaped and blended intoa square beam 20 mm wide×20 mm. Emitted light may be 90% polarized in amajority state p resulting in light beams 703 and 704. The emitted lightbeams 703 and 704 may be incident on polarizers 705 and 706,respectively. Polarizers 705 and 706 may reflect minority states-polarization to result in light beams 709 and 7010, which may beincident on a beam dump 7011. Polarizers 705 and 706 may transmitp-polarization to result in light beams 706 and 707, which may beincident on polarization rotating optically addressed light valves 712and 13, respectively. Each of light valves 712 and 713 may have the sameimage applied to light beams 706 and 707 to create polarizationpatterns, and may spatially flip 20% of the “pixels” from p-polarizationto s-polarization in the desired patterns resulting in light beams 714and 715. Beams 714 and 715 may be incident on polarizers 716 and 717,respectively. Polarizers 716 and 717 may reflect s-polarization toresult in light beams 718 and 719, respectively, which may contain 20%of the energy and may be dumped to a beam dump 720. Polarizers 716 and717 may transmit p-polarization to result in light beams 721 and 722.Beam 722 may be incident on a half wave plate 723 which rotates thepolarization of every photon by a half wave, thereby turningp-polarization to s-polarization to result in light beam 724. Beams 721and 724 may be incident on mirrors 725 and 726, respectively, to resultin light beams 727 and 728. Beam 727 may be incident on mirror 729 toresult in beam 730, which may be incident on polarizer 731 inp-polarization. Beam 728 in s-polarization may be incident on polarizer731 which may reflect s-polarization of beam 728 and transmitp-polarization of beam 730 to result in light beam 732. Beam 732 may bea beam of twice the intensity of a single polarization state from lightsource 701 or 702, for a total initial intensity of 1.8× the originaldue to the 90% initial polarization, and proportionally less that forthe 20% of the polarization map image applied at light valves 712 and713. Total propagated intensity at beam 732 may be 1.44× the initialintensity for a total transmitted power of 47.52 kW emitted. Imaged tothe original 20×20 mm square, the final intensity may be 11.88 kW/cm2 ifdivergence angle is maintained.

In powder bed fusion additive manufacturing, a source image of anoptical beam of sufficient energy is directed to locations on the topsurface of a powder bed (print surface) to form an integral object whena powdered material is processed (with or without chemical bonding). Theresolution (or a pixel size) of an optical system used for powder bedfusion additive manufacturing depends on whether the print surfacecoincides with the focal plane of the final optics in the opticalsystem, or in term for imaging systems, depending on whether thedistance between lenses and image planes for optics performing animaging operation stays substantially a constant distance for a givenlens configuration. To be able to print large objects in powder bedfusion additive manufacturing, accurate control of the image location onthe print surface, and distance between lenses is necessary to maintainthe resolution or the pixel size on every possible location of the topsurface of the powder bed. Different powdered materials may requiredifferent intensities or energies of the optical beam as the respectivethresholds of bonding energies are different. If a change in theintensity is required when changing the powder type or the powder sizedistribution, the optical system may need to be shut down forre-installation and re-alignment of the imaging lenses.

To address the problems related to intensity and resolution changes, aprocess is described as follows. FIG. 8 is a flow chart 800 illustratingsteps for use of a dynamic optical assembly that can include an imagerelay gantry. In step 810, information is obtained or otherwisedetermined to find a minimum resolution (a pixel size of an incidentlight) for an object to be printed in the powder bed fusion additivemanufacturing system. According to the intensity and resolutionrequirements, a magnification ratio of the incident light containing animage information and an image distance of dynamic optical assembly iscalculated. The magnification ratio may transfer a first size of theimage at a precursor image plane to a second size of the image at theprint surface (top surface of a powder bed). The incident light may beoriginated from energy source and passes through the precursor imageplane at which the image information may be created. Process 800 mayinvolve storing geometrical data of the object, positional androtational control data of the dynamic optical assembly.

At step 820, process 800 can include configuring a mechanical assemblyand one or more of lens assemblies to achieve the magnification ratioobtained at 810 suitable for the powdered material. The configuring ofmechanical assembly and one of lens assemblies may involve a rotation ofmechanical assembly, a swap of second sets of optical lenses, or aremoval of a second set of optical lenses.

At step 830, a plurality of rotations can be performed to direct theincident light from the precursor image plane to the print surface at adesired location on the print surface (e.g., top surface of a powderbed) in each successive step of powder bed fusion additivemanufacturing. At step 840, the dynamic optical assembly can perform aplurality of translational movements to maintain a constant imagedistance from the precursor image plane to every location of the printsurface (e.g., top surface of a powder bed) in each successive step ofpowder bed fusion additive manufacturing. Vertical motion of the powderbed or the optical assembly can be used to maintain a fixed separationof the powder bed with respect to a final lens.

An apparatus to implement process 800 can include a layer of a powderedmaterial dispensed on a top surface of a powder bed supported by a buildplatform. Source image of an incident light located at a precursor imageplane is incident upon lens assembly in barrel. Lens assembly may beconfigured by a rotation of barrel that effect a swap of a second set ofoptical lenses, a removal of a second set of optical lenses, use ofdynamic lenses that change shape, electronic lens swapping, beamredirect systems, electro-optically controlled refractive beam steeringdevices, or a combination thereof, to have a suitable magnificationratio for the powdered material. Object image of a size different thansource image appears after passing through lens assembly, and ismodified according to the magnification ratio of lens assembly. The beamcontaining image information of is incident on precursor mirror and isdirected to mirror mounted on compensating gantry where it reflects offmirror and then is incident on final mirror mounted on build platformgantry. Final mirror directs the beam containing image informationthrough a final lens toward a top surface of a powder bed and objectimage is recreated and magnified in image plane which may be formedthereon. The powdered material on powder bed may melt to form a shape ofobject image. Build platform gantry then moves to a next location untildesignated locations on the top surface of powder bed are bonded forthat layer. A new layer of the powdered material is dispensed again andthe build platform may move down a distance equal to the thickness ofthe layer of the powdered material to keep a constant distance to thebuild platform gantry. The cycle starts for the new layer in continuingthe additive printing process.

FIG. 9A illustrates an example scenario 900 of an intermediate point ina powder bed fusion additive manufacturing printing process inaccordance with the present disclosure. Example scenario 800 showsupward movements of components in the build chamber while controllingthe depth of field with a stationary build platform 930. Build platform930 may have an area of 0.5 meter by 1 meter on which powders may bedispensed during a print cycle. In one embodiment, build platform 930 ismoved into position beneath gantry table 905 and locked into position.Vertical columns 903(1)-903(4), each of which at a height of 3 meters,support a gantry 907 mounted on the gantry table 905. A powderdispensing unit 910, a compacting functionality 911, and a mirror 917may be mounted on gantry 907 for translational movements in a horizontalplane. Gantry table 905 is shown at a position higher above powder bed920 in FIG. 8 to reflect that printing may be in progress. Powder bed920 contains both powder layers and printed object(s) in various stagesof completion. A new layer of powders 925 is dispensed from powderdispensing unit 910 that includes powder spreading and compacting. Beam921 incident from print head (not shown) may be reflected off a mirror917 to become beam 922 impinging upon a location 923 in the new layer ofpowders 925. Printing can occur by melting, sintering, fusing, orotherwise amalgamating of powders at location 923 in the new layer ofpowders 925. The distance between mirror 917 and the location 923 in thenew layer of powders 925 is the depth of field that needs to be tightlycontrolled to satisfy a resolution requirement. An arrow 970 indicatesan upward movement of gantry table 905, which supports gantry 907,powder dispensing unit 910, mirror 917, and in certain embodiments, asurrounding chamber or wall. During this process, the build platform 930remains locked into place, and the gantry 907 (and/or chamber andchamber wall) moves relative the build platform 930. This arrangement isparticularly useful for embodiments discussed below, in which the buildplatform 930 is large, and will need to support a large amount of heavymaterial that is not easily moved in a vertical direction with requiredprecision.

In some embodiments, build platform 930 of example scenario 900 may havean area of more than 0.25 square meters. Alternatively, build platform930 of example scenario 900 may have an area of more than 0.5 squaremeters. Alternatively, build platform 930 of example scenario 900 mayhave an area of more than 1 square meters. Alternatively, build platform930 of example scenario 900 may have an area of more than 5 squaremeters. Alternatively, build platform 930 of example scenario 900 mayhave an area of more than 10 square meters. Alternatively, buildplatform 930 of example scenario 900 may have an area of more than 50square meters.

In some embodiments, powder bed 920 including the printed object ofexample scenario 900 may have a mass of more than 10 kilograms.Alternatively, powder bed 920 including the printed object of examplescenario 900 may have a mass of more than 50 kilograms. Alternatively,powder bed 920 including the printed object of example scenario 900 mayhave a mass of more than 100 kilograms. Alternatively, powder bed 920including the printed object of example scenario 900 may have a mass ofmore than 500 kilograms. Alternatively, powder bed 920 including theprinted object of example scenario 900 may have a mass of more than1,000 kilograms. Alternatively, powder bed 920 including the printedobject of example scenario 900 may have a mass of more than 2,000kilograms. Alternatively, powder bed 920 including the printed object ofexample scenario 900 may have a mass of more than 5,000 kilograms.Alternatively, powder bed 920 including the printed object of examplescenario 900 may have a mass of more than 10,000 kilograms.

In some embodiments, build platform 930 of example scenario 900 may havean area of more than 0.25 square meters and powder bed 920 including theprinted object of example scenario 900 may have a mass of more than 10kilograms.

Powder bed fusion technique process powdered materials to form integralobjects out of metal, ceramic, and plastic powders. Sufficient energiesare needed to bring powders to the respective melting/sintering/alloyingtemperatures, or phase transition temperatures. If a powdered materialstarts out closer to its phase transition temperature, less energy maybe required to complete the phase transition. The powder bed fusionadditive manufacturing may benefit from pre-heating of the powder bed toreduce the amount of energy delivered by the lasers or other energysources. This may allow using a lower intensity laser and less dwelltime to bond a powder, increasing the throughput rate.

Post processing heat treatments may be required for some powderedmaterials such as metals to mitigate stress concentrations and increasemechanical strengths. Post processing heat treatments may include acontrolled-temperature anneal or a fast cooling to improve desiredmechanical or electrical properties. Pre-heating of powders and postprocessing heat treatments may be achieved by embedding heating/coolingelement(s)/temperature sensor(s) inside walls of a build chamber/insidea build platform and controlling the rate of heating/cooling with afeedback algorithm. Heat loss may be reduced by using insulatingmaterials inside walls of a build chamber.

A suitable thermal management system for use in conjunction with thedescribed powder bed and chamber is discussed with respect to FIG. 9B.FIG. 9B illustrates an example apparatus of laser-based powder bedfusion additive manufacturing system 900B in accordance with anembodiment of the present disclosure. The system 900B includes both anenergy source 950 and energy beam steering systems/drivers 955 as partof a printhead 910B. An optical-mechanical assembly 930(1)-930(N) candistribute energy beams for the printhead 910B through the system 900B.Data input, monitoring, control, and feedback control using varioussensors is enabled by processor(s) 901 and memory 940. These systems caninclude input of 3D object data 941, print head control 942, buildplatform control 943, optical-mechanical assembly control 944, and buildchamber control 945

Laser-based powder bed fusion additive manufacturing system 900 mayinclude one or more build chambers. For illustrative purpose and withoutlimitation, one or more build chambers of system 900 are shown in FIG.9B as build chambers 920B(N), with N being a positive integer greaterthan or equal to 1. Build chambers 920B(1)-920B(N) may include powderdispensing units 922(1)-922(N) for dispensing powdered materials andbuild platforms 924(1)-924(N) to support powder beds formed by powderedmaterials. Each of build chambers 920B(1)-920B(N) may have a differentsize and may be swappable among each other within powder bed fusionadditive manufacturing system 900. Build chambers 920B(1)-920B(N) mayhave removable doors to facilitate powder removal from a side of buildchambers 920B(1)-920B(N) after a build. Build chambers 920B(1)-920B(N)may be sealed in an atmosphere during powder bed fusion additivemanufacturing. The atmosphere may include, but not limited to, vacuum,air, nitrogen, argon, or helium.

In some embodiments, walls/ceilings of build chambers 920B(1)-920B(N)may be embedded with heating/cooling elements 926(1)-926(N) andtemperature sensors 928(1)-928(N) to control the thermal environmentinside build chambers 920B(1)-920B(N).

In some embodiments, heating/cooling elements 926(1)-926(N) may be fluidchannels capable of heat exchange. The fluid may be heated or cooledoutside build chambers 920B(1)-920B(N) and perform heat exchange withthe walls/ceilings by moving fluid through the fluid channels. The fluidmay include, but not limited to, an oil, water, steam, air, nitrogen,argon, or a coolant.

In some embodiments, heating/cooling elements 926(1)-926(N) may beresistive heating elements and thermionic cooling elements respectively.

In some embodiments, temperature sensors 928(1)-928(N) may bethermocouples embedded inside walls/ceilings of inside build chambers920(1)-920(N).

In some embodiments, temperature sensors 928(1)-928(N) may be infraredcamera(s) mounted on walls/ceilings inside build chambers 920(1)-920(N).

In some embodiments, each of build chambers 920(1)-920(N) may includeradiation shields on walls/ceilings of build chambers 920(1)-920(N) toreduce heat loss.

In some embodiments, build chambers 920(1)-920(N) may include lowthermal conductance materials as parts of walls/ceilings.

In some embodiments, each of build platforms 924(1)-924(N) may becapable of vertical motions or being fixed at a given height duringpowder bed fusion additive manufacturing. Build platforms 924(1)-924(N)may have different sizes and support variable masses of powder beds.Build platforms 924(1)-924(N) may be removable from build chambers920(1)-920(N) on rails, wheels or other means.

FIG. 10 describes a method to minimize powder volume requirements duringa build operation. Process 1000 may be utilized to realize printingvariable print chamber walls for powder bed fusion in a powder bedfusion additive manufacturing system in accordance with the presentdisclosure. At 1010, process 1000 may involve dispensing a powderedmaterial to form a first layer of a powder bed on a support surface of abuild platform.

At 1020, process 1000 may involve selectively fusing a portion of thefirst layer of the powder bed to form one or more first walls out of thefused portion of the first layer of the powder bed. The one or morefirst walls may contain another portion of the first layer of the powderbed on the build platform. In some embodiments, the one or more firstwalls may include multiple walls surrounding an area interior of thebuild platform to create a region devoid of the powdered material. At1030, process 1000 may involve dispensing the powdered material to forma second layer of the powder bed on the first layer of the powder bed.At 1040, process 1000 may involve selectively fusing a portion of thesecond layer of the powder bed to form one or more second walls out ofthe fused portion of the second layer of the powder bed. The one or moresecond walls may contain another portion of the second layer of thepowder bed.

In some embodiments, the one or more first walls may include multiplefirst walls surrounding another portion of the first layer of the powderbed over a first area of the build platform. Moreover, the one or moresecond walls may include multiple second walls surrounding anotherportion of the second layer of the powder bed over a second area of thefirst layer of the powder bed, with the second area being smaller thanthe first area.

In some embodiments, the one or more first walls may include at leastone wall along at least one perimeter of multiple perimeters of thebuild platform. Additionally, the remaining one or more perimeters ofthe multiple perimeters of the build platform may border one or morestructural walls. In some embodiments, process 1000 may further involvecausing a relative movement between the build platform and the one ormore structural walls in a direction perpendicular to the supportsurface of the build platform. Moreover, process 1000 may involvedispensing the powdered material on the first layer of the powder bedand the one or more first walls to form a second layer of the powderbed. Furthermore, process 1000 may involve selectively fusing a portionof the second layer of the powder bed to increase a height of the one ormore first walls.

In another embodiment, temporary walls can be produced to have pipes,cavities, or porous sections (hereinafter “fluid passageways”) able tosupport fluid flow. The fluid passageways can be open, or partiallyclosed, and can be formed to interface with external pipes, hoses,sprayers, or other fluid communication systems. Air, nitrogen, water,high temperature or silicone oils, or other suitable gas or liquid canbe circulated or otherwise transferred through a fluid passageway toimprove thermal management. Thermal management can include both fast orcontrolled cooling, and the fluid can be circulated (e.g. through pipesformed in the temporary walls) or sprayed, dripped, or splashed against,for example, a porous outer wall section.

The proposed scheme may be implemented in powder bed fusion additivemanufacturing systems for printing metal, plastic, or ceramic parts.Applications of the proposed scheme may be more specifically defined asfor use in the print bed part of the machine on the receiving end of thelaser or electron beam. In various embodiments of the presentdisclosure, one or more energy sources of a print head of a powder bedfusion additive manufacturing system may be controlled to print walls ofa build chamber. This allows for elimination of the edge walls of thechamber, and can allow for sub-set areas to be created. The presence ofsub-set areas/volumes/voids can help minimize powder usage, and enablesthe creation of volumes devoid of powder. This is especially useful whenworking with expensive materials such as gold, silver, and copper, andis also useful for working with very large objects where the excesspowder can include a very large portion of the standard print volume.Under the proposed scheme, powder may be selectively distributed acrossthe build area in pre-defined walled areas created during the additivemanufacturing process.

Since the print bed and the print head are typically verticallyseparated for successive layers, there is a need for print chamber wallsto support previously deposited layers consisting of powder and printedobject(s). One example may involve raising to a close-fitting wall.Another example may involve printing a perimeter wall (and perhapsstructural support for it) during each layer. This wall may be cut outand recycled after each print.

In some embodiments, most or all of the surrounding walls may be raised,and a wall may be also printed to lessen the powder bed area for thelayer of powder while using a “tub” formed by the surrounding walls forcatchment of powder falling outside the printed wall.

In some embodiments, the raised wall may be not intended as a fullperimeter. For instance, access points for a fork lift or other materialhandling equipment may be needed when the print bed is first put intothe print station and later when the completed bed (powder and printedobject(s)) are lifted out. The printing of a limited wall for this areaprovides the required remaining wall to support the powder during aprint cycle. The material handling equipment potentially can then“punch” through this printed wall to gain access to the lift points. Insome embodiments, the lift points may be determined by an algorithm oruser placement a priori the build and are built into the walls in keylocations.

The printed wall does not need to match geometry of the print table, norexactly match a wall printed in a previous layer. This allows, with theappropriate powder dispensing equipment and logic, powder to bedispersed just enough to cover between the walled areas where powder isneeded. Advantageously, this can save a tremendous amount of time,weight and/or powder per layer.

FIG. 11A illustrates an example scenario 1100 in which a powder bed 1120is formed on a build platform 1130 in accordance with the presentdisclosure may be utilized. The build platform 1130 may have an area of0.25 square meter and may support a powder bed 1120 of a powderedmaterial, which may be 0.5 m deep inside a build chamber 1110. Scenario1100 may be at the end, or in the middle of a print cycle. Below thebuild platform 1130 is a hopper 1140 with sloped walls which may be45-60 degrees relative to a horizontal surface on which build platform1130 is disposed. In some embodiments, hopper 1140 may contain an auger1150.

FIG. 11B illustrates another example scenario 1101 in which theseparation of a powder bed 1121 from a build platform 1131 is depicted.Scenario 1101 may be at the end of a print cycle or in a mid-cycle thatis aborted due to various reasons. Inside a build chamber 1111, a buildplatform 1131 supporting the powder bed 1121 may be tilted over 90degrees from a horizontal position. The gravity pull due to the weightof the powder bed 1121 causes the powdered material and the printedobject(s) embedded within the powder bed 1121 to fall in a hopper 1141below. The build chamber 1111 may include a vacuum 1160 and a highpressure jet 1162 so that a substantial portion of powders may becollected in the hopper 1141. The vacuuming 1160 and gas-jetting 1162may be utilized to dislodge sticky powders remained on the buildplatform 1131 after tilting the build platform 1131. The hopper 1141 mayhave sloped walls to help guide powders onto the bottom of the hopper1141. The hopper 1141 may include an auger 1151.

Processing can involve controlling a powder dispensing assembly todispense a plurality of layers of a powdered material in forming apowder bed during a print cycle. Vertical motion of powder dispensingassembly can be controlled to maintain a constant separation from thepowder bed. The vertical motion results in indexing powder dispensingassembly can be away from the powder bed (e.g., upwards) by a distanceequivalent to a thickness of a dispensed powder layer after a portion ofdispensed powder layer is bonded together. To remove leftover powder,movement of the build platform may include rotating, tilting, inverting,vibrating, shaking and/or jittering. As a result of these motions, thepowder bed on build platform may fall into hopper below build platformdue to weight of the powder bed. Vacuum systems, mechanical arm, and/orgas sprayer can be used to further dislodge remaining powders on buildplatform. Thus, a substantial portion of the powdered material may becollected in hopper for reuse or for storage. In some embodiments, anauger and/or conveyer can be used to transport collected powders inhopper towards one or more of storage chambers. In another processembodiment, a substantial portion of the powdered material can be sealedin one or more of storage chambers an atmosphere suitable for thepowdered material. The atmosphere may include vacuum, air, nitrogen,argon, helium, other inert gas, or noble gas.

FIGS. 12A and 12B illustrates a system for long part manufacture. Manycurrent 3D printers have significant and recurrent downtime when a buildchamber must be emptied of powder and printed parts and reset for thenext print job. In the following description, a uniform coordinatesystem 1211 is defined. Accordingly, certain systems may correspond toor define longitudinal, lateral, and transverse directions 1211 a, 1211b, 1211 c that are orthogonal to one another. The longitudinal direction1211 a may correspond to a long axis of a system. Accordingly, duringadditive manufacture, a long axis of a long part 1210 may besubstantially aligned with the longitudinal direction 1211 a. Thelateral direction 1211 b may combine with the longitudinal direction1211 a to define a horizontal plane. That is, the longitudinal andlateral directions may both extend within a horizontal plane. Thetransverse direction 1211 b may extend up and down in alignment withgravity.

In selected embodiments, systems and methods in accordance with thepresent invention may enable or support substantially continuousadditive manufacture that does not have such downtime. As can be seenwith reference to FIGS. 12A and 12B, this may be accomplished bymanufacturing a part 1210 in segments. For example, a system can (1)manufacture a first segment 1212 a of a part 1210, (2) advance the part1210 a selected distance down a conveyor 1216, (3) manufacture a secondsegment 1212 b of the part 1210, (4) advance the part 1210 a selecteddistance down the conveyor 1218, and (5) repeat until all segments ofthe part 1210 have been completed. In this manner, additive manufactureand clean-up (e.g., separation and/or reclamation of unused orunamalgamated granular material) may be performed in parallel (i.e., atthe same time) at different locations or zones on the conveyor. Thus,additive manufacture in accordance with the present invention need notstop for removal of granular material and/or parts.

A system can define or include multiple zones 1236 a-c. Different tasksmay be performed in different zones. In selected embodiments, differentzones may correspond to different locations along a conveyor.Accordingly, a conveyor may advance (e.g., translate in directionindicated by arrow 1232) a part through the various zones of a system.In certain embodiments, a system may include three zones 1236 a, 1236 b,1236 c. A first zone 1236 a may correspond to, include, or span theportion of a conveyor where additive manufacture occurs. Thus, a firstzone 1236 a may correspond to the area on a conveyor where the variouslayers of granular material 144 are being laid down and granularmaterial is being maintained in intimate contact with a part.

A second zone 1236 b may directly follow a first zone 1236 a. A secondzone 1236 b may be characterized by a significant portion of theunamalgamated portion of a granular material moving away from a part.For example, in a second zone 1236 b, one or more walls may terminate orbe removed so that the unamalgamated portion of a granular material mayno longer be fully contained in the lateral direction 1211 b. As aresult, some of the unamalgamated portion of a granular material mayspill off the sides of one or more plates, a conveyor, or the like. Thespilling granular material may fall into one or more containers where itmay be collected and reused.

A third zone 1236 c may directly follow a second zone 1236 b. A thirdzone 1236 c may be characterized by a portion of a part 1210 within thethird zone 1236 c being exposed to view (e.g., completely,substantially, or partially exposed to view by the removal or movementof a significant portion of the unamalgamated portion of a granularmaterial) without the part 1210 changing its position in the lateral andtransverse directions 1211 b, 1211 c.

For example, in certain embodiments, a leading portion of a part 1210may reach a third zone 1236 c while a trailing portion of the part 1210is still being manufactured within the first zone 1236 a. Accordingly,in selected embodiments, a conveyor, one or more plates, one or moretemporary supports 1223, one or more walls, or the like or a combinationor sub-combination thereof may cooperate to maintain a leading portionof a part 1210 in the same position in the lateral and transversedirections 1211 a, 1211 c as the leading portion occupied within thefirst zone 1236 a and the second zone 1236 b. Thus, the position of theleading portion of the part 1210 may not excessively disrupt, distort,or the like additive manufacture that is occurring on a trailing portionof the part 1210 in the first zone 1236 a.

In selected embodiments, all of the unamalgamated portion of a granularmaterial that is external to a part 1210 may be removed in the secondzone 1236 b or within some combination of the second and third zones1236 b, 1236 c. However, in certain alternative embodiments, a bed maybe removed from a conveyor with four walls intact. Accordingly, all orsome remainder of the unamalgamated portion of a granular material maybe removed at a station that is spaced some distance from a first zone1236 a.

In another embodiment, a ramp may be used to transition from a lowersegment or zone to a subsequent, higher segment or zone. For example, aramp may enable a trailing wall corresponding to a lower segment to bebuilt up higher by a process of additive manufacture than the majorityof the lower segment so that the trailing wall can become a leading wallfor a subsequent, higher segment. Building a ramp may be much fasterthan laying down complete layers (e.g., layers covering the entire lowersegment) when only the trailing wall is being built up.

A ramp may include a plurality of layers of granular material whoselength in one or more directions (e.g., the longitudinal direction 1211a) is incrementally changed. For example, within a ramp, each successivelayer may be shorter in length than the immediately preceding layer. Theresulting angle of a ramp with respect to the horizontal may be lessthan a critical angle of repose for the granular material. Accordingly,the granular material forming the ramp may be stable and not slough offor move due to the acceleration of gravity acting thereon.

In operation, a first layer of granules of the granular material can bedistributed and radiant energy directed at all granules within the firstlayer that form part of the selected granules. A second layer ofgranules of the granular material is distributed over the top of thefirst layer and radiant energy directed at all granules within thesecond layer that form part of the selected granules. The first layercan define a first plane and the second layer defines a second planethat is parallel to the first plane. In certain embodiments, the firstand second planes are both horizontal planes. In other embodiments, thefirst and second planes both extend at an angle with respect to ahorizontal plane that is greater than zero and less than or equal to acritical angle of repose of the granular material, forming a ramp.

FIG. 13A illustrates an additive manufacturing system 1300 that includesa powder chamber 1302 with a powder bed 1304. The system 1300 can alsoinclude a processing platform 1320, which can be a designated processingarea, another powder chamber, a coating station, a conveyor, a shippingcontainer, or any other needed manufacturing system component. Thesystem 1300 also includes a robot arm 1310 with manipulator 1312 capableof grasping a part 1330 by its additively manufactured manipulationpoint 1332. Sensor systems 1334 can be mounted on the robot arm 1310, oralternatively, on, in, or near the powder chamber 1302.

While a six degree of freedom single robot arm with clamping graspers isa manipulation device shown in the Figure, other automated, mechanicalor manual embodiments can be employed. For example, cranes, lifts,hydraulic arms, clamps, tracks or rails, pinning mechanisms, or anyother type of manually or automatically controllable manipulation devicecan be used. A manipulation device can be mounted beside, on, near, orwithin the powder chamber 1302. Alternatively, a manipulation device canbe movably mounted on rails over, near, or positioned within the powderchamber. Multiple manipulation devices can be used in some embodiments

A manipulation device can include position, depth, laser scanning, orsimilar sensor systems 1314. Sensors can be mounted on or near themanipulator, elsewhere on the robot arm, or on, near, or within thepowder chamber or processing platform 1320. In certain embodiments, asensor can be movable, with hinged, rail, hydraulic piston, or othersuitable actuating mechanisms used to rotate, elevate, depress,oscillate, or laterally scan the sensor. In certain embodiments,conventional RGB CMOS or CCD sensors can be used, alone or incombination specialized depth sensors or optical edge tracking sensesystems. Embodiments can be selected to improve 3D localization of apart, including identification and use guides, markers, or otherdetectable positioning indicia.

FIG. 13B illustrates the system described with respect to FIG. 13A, withthe robot arm 1310 lifting and reorienting a part 1330 by one of itsadditively manufactured manipulation points 1332. In some embodiments,the part 1330 can be lifted, rotated, linearly translated, and set backonto the powder bed 1304 for further processing.

FIG. 13C illustrates the system described with respect to FIG. 13A, withthe robot arm 1310 lifting and reorienting a part 1330 by one of itsadditively manufactured manipulation points 1332. In this embodiment,the part 1330 lifted, rotated, and set onto the processing platform 1320for further processing.

FIG. 14 illustrates a part 1400 including various possible additivelymanufactured robot manipulation points. Part 1400 supports variousprojecting structures (i.e. 1402, 1404, 1406, 1408, and 1414), as wellas internal structures or cavities (i.e. 1410, 1412, and 1416), capableof acting as robot manipulation points. In the Figure, structure 1402 isa lunate tab having two narrow connection points to part 1400. The tabportion allows for easy engagement with manipulators having nipping orpinching graspers, while the narrow connection points simplify removalof the structure 1402 by mechanical clipping, sawing, punching, ordrilling; or by directed energy beams. Similarly, pin 1404 is a smallprojecting structure capable of being engaged by nipping or pinchinggraspers, or by a “bit” holding type engagement system that surroundsand constricts to hold the pin 1402. Rectangular tab 1406 is attached ata single narrow point, allowing some embodiments of the manipulator totwist and break free the tab after the part has been moved to a desiredarea/position. Plate 1408, again attached at two points to simplifylater removal by mechanical clipping or energy beams, is relatively longand broad to simplify the engagement by the manipulator.

Additive manufacturing of the part 1400 can be designed to includedepressions, lands, cavities, holes, or other internally definedstructures that do not greatly affect part function, but improvereliability of engagement with the robot arm. For example, prismaticlocking cavity 1410 can guide a pin or clamp system into engagement withthe cavity. Alternatively, spreading grippers can be used to engage anotch 1412 defined in the part 1400. Cavities or openings 1416 can alsobe defined in removable projecting tabs 1414 if needed. In someembodiments, cavities or opening in a substantially additivelymanufactured part can be defined by subtractive machining, drilling,punching, or removal of material be etching or directed energy beams. Incertain other embodiments, after use the cavities can be filled usingadditive manufacturing techniques, by use of thermoset plastics, or anyother suitable fill technique.

In some embodiments, two or three-dimensional positioning of the part1400 can be improved by use of imaging or other optic sensors thatidentify precise position of the part using projecting tab or cavityposition. In other embodiments, marking optical guides or indicia 1420can be additively formed or mechanically or laser inscribed on theprojecting structure or the part itself to improved guidance forengagement of 3D positioning after movement.

In one embodiment, processing can occur with the following steps. In afirst step, material is positioned on a powder bed in a powder chamber.Then, using directed beams of two-dimensionally patterned energy, a partis manufactured that includes one or more manipulation points. Themanipulator can engage the manipulation point, and lift the part awayfrom a powder bed. The part can be repositioned on the powder bed forfurther processing, or alternatively moved to a new processing area awayfrom the powder bed and chamber. In an optional step, the manipulationpoint can be removed (e.g. a projecting tab is mechanically clipped), orinfilled (e.g. additively defined holes or cavities filled with an epoxyresin).

FIG. 15 illustrates an example process 1500 of collecting andcharacterizing powder samples of a powdered material during a printprocess. Process 1500 may be utilized to collect the powder samples froma powder bed or a powder distribution assembly, and characterizing thepowder samples in real-time in a test suite in accordance with thepresent disclosure. At 1510, process 1500 may involve controlling aningester to collect a plurality of powder samples of a powdered materialin forming a printed object during a print cycle. The powdered materialmay include metal, ceramic, plastic powders, or other suitable powdersable to bond together while subjected to a thermal energy. The ingestercan collect powder samples periodically at a predetermined interval orrandomly or at predetermined stages during a print process. For example,powder samples can be collected at every 10-minute interval or only at⅕th and ⅘th completion of a print process. Ingester may have a mechanismfor diverting incoming powder from a powder bed or powder dispensingassembly. The ingester may also control an amount of powders beingdiverted, depending how many tests are required for analysis. At 1520,process 1500 may involve controlling a test suite to perform one or moretests of test. In some embodiments, one or more specific properties of apowdered material may need to be tightly controlled within a certainrange to guarantee the mechanical, electrical, or optical properties ofthe printed object. In other embodiments, characteristics of powdersduring a print process may need to be retained for auditing purposes.Test suites may include instruments having capabilities to perform oneor more tests. For illustrating purposes and without limitation, onetest may measure a distribution of powder sizes by particle sizeanalyzer; a second test may measure a density of powder samples bypycnometer; a third test may identify substances within the powdersamples by gas chromatography mass spectrometry. At 1530, process 1500may involve determining whether to modify a set of printing parametersemployed for the print process or whether to abort the print processaccording to a result characterization from test(s). The determinationmay include computer simulations based on a set of models using resultsof the characterizations as input. Powder samples may have undergoneundesired changes for powders without certification or inadequateprocessing conditions. Tests may provide a real-time feedback on theproperties of powders during the print process. One or more printingparameters can be modified according to results of tests. For example,incident beam intensity may be increased or decreased when gaspycnometer measures a deviation of specified powder density which mayaffect the energy per unit volume required to melt or sinter thepowders. Dwell time of the incident beam provided by a print head or athickness of powder layer dispensed by powder dispensing assembly canalso be controlled to adjust for the energy requirement change. If thedeviation of the energy per unit volume to the specified powder densityis too large, the print process can be halted or aborted since theenergy source inside print head may not meet the requirement to melt thepowders. In another example, contaminations within powder samples may bedetected by gas chromatography mass spectroscopy, which may affect oneor more electrical, mechanical and optical properties of the printedobject. In still other embodiments, the print process can be stopped ifcharacterization results indicate usage of unlicensed powders ordangerous powders, including unlicensed powders likely to result ininferior additive manufacturing results.

In some embodiments, prediction of final print quality based on theresults of in-process (in real-time or in-situ) characterizations ofpowder samples may be performed by simulations using a set of models.For example, dimensional controls of the printed object may rely on aresolution of the incident beam and a temperature gradient of powdersacross the boundary of melted region. The melted region may expandbeyond the intended boundary if the temperature does not drop quickenough across the boundary and result in exceeding the tolerance of thedimensional requirement. The temperature gradient may be simulated by aheat transfer model which calculates a heat conduction rate based onproperties of powders such as on the compositions and sizes of powders.If the predicted dimension of a printed object by the simulation modelexceeds the tolerance of dimensional requirement, the print process canbe aborted.

At 1540, process 5100 may involve storage of powder samples in aplurality of sample canister. The sample canisters may be stored foranalyses that may not be suitable for in-process characterization or forauditing purposes later. Storage containers may be capable of packagingpowder samples in an atmosphere substantially equivalent to thein-process (in real-time or in-situ) atmosphere inside sample canisters.The atmosphere may be vacuum, air, or an inert gas such as nitrogen,carbon dioxide, argon, helium, or other noble gas.

Referring to FIG. 16 , a manufacturing facility 1624 in accordance withthe present invention may comprise one or more machines 1610 containedwithin an enclosure 1626. Such an enclosure 1626 may control one or moreenvironmental conditions as desired or necessary. For example, anenclosure 1626 may protect a printed or to-be-printed material fromunwanted thermal, chemical, photonic, radiative, or electronic reactionsor interactions or the like or combinations or sub-combinations thereof.An enclosure 1626 may also protect human operators or other nearbypersonnel from potentially harmful aspects of a machine and machinepowders 1610 such as heat, UV light, chemical reactions, radioactivedecay products, and laser exposure.

The one or more machines 1610 contained within a particular enclosure1626 may all be the same size or of varying sizes. Similarly, the one ormore machines 1610 contained within a particular enclosure 1626 may allbe the same type or of varying types. For example, in selectedembodiments, each of the one or more machines 1610 within an enclosure1626 may amalgamate (e.g., unite, bond, fuse, sinter, melt, or the like)a particular granular material in a batch process. In other embodiments,each of the one or more machines 1610 within an enclosure 1626 mayamalgamate a particular granular material in a continuous process. Instill other embodiments, one or more machines 1610 within an enclosure1626 may amalgamate a particular granular material in a batch process,while one or more other machines 1610 within the enclosure 1626 mayamalgamate the particular granular material in a continuous process.

In certain embodiments, a manufacturing facility 1624 may include one ormore airlocks 1628 forming one or more antechambers for a correspondingenclosure 1626. An airlock 1628 may enable parts, material 144,personnel, or the like to pass into and out of an enclosure 1626 withoutcompromising the environment (e.g., the low oxygen and inert gasenvironment) within the enclosure 1626. An airlock 1628 may include atleast two airtight (or substantially airtight) doors 1630 a, 1630 b. Afirst door 1630 a of an airlock 1628 may enable parts, materials 144,personnel, or the like to pass between the interior of the airlock 1628and the interior of the corresponding enclosure 1626. A second door 1630b may enable parts, materials 144, personnel, or the like to passbetween the interior of the airlock 1628 and an exterior environmentsurrounding the corresponding enclosure 1626. An airlock 1628 may alsoinclude an gas exchange system (not shown) that may purge and/or ventthe airlock 1628 as desired or necessary to efficiently transition thegaseous environment within the airlock 1628 between a state compatiblewith the interior of the enclosure 1626 and a state compatible with theenvironment exterior to the enclosure 1626.

One or more machines 1610 may be arranged in an enclosure 1626 so thatsufficient space around the machines 1610 is preserved for one or morehuman workers, robots, or the like to access the machines 1610, removeparts therefrom, vacuum up unamalgamated granular material 144 forreuse, or the like. Alternatively, or in addition thereto, an enclosure1626 may include various gantries, catwalks, or the like that enable oneor more human workers, robots, or the like to access the machines 1610(e.g., visually access, physical access) from above. This may be helpfulwhen an enclosure 1626 contains one or more large machines 1610 whereaccess from the edges or sides thereof may be insufficient for certaintasks.

In certain embodiments, a manufacturing facility 1624 may include one ormore gas management systems 1632 controlling the make-up of gaseousmatter within an enclosure 1626. A gas management system 1632 maymaintain concentrations of inert or substantially inert gas (e.g.,vacuum, nitrogen, argon, carbon-dioxide, or the like or a combination orsub-combination thereof) above a desired level (e.g., argon at or aboveabout 99.9% by volume). Alternatively, or in addition thereto, a gasmanagement system may maintain concentrations of oxygen and/or watervapor below atmospheric levels. For example, in one embodiment a desiredlevels can be below 0.05% by volume for gaseous oxygen, and below 0.05%by volume for water vapor.

The gaseous environment within an enclosure 1626 may be incompatiblewith the respiratory requirements of one or more humans that may need toenter and/or work within the enclosure 1626. Accordingly, to work withincertain enclosures 1626 in accordance with the present invention, one ormore workers may don personal protective equipment (PPE). Thereafter,when the worker enters an enclosure 1626, the PPE may create a barrierbetween the worker and the working environment within the enclosure1626.

In selected embodiments, the PPE worn by one or more workers may includea self-contained breathing apparatus (SCBA). A SCBA may be a closedcircuit device that filters, supplements, and recirculates or storesexhaled gas (e.g., a rebreather). Alternatively, SCBA may be an opencircuit device that exhausts at least some exhaled gas (e.g., nitrogen,carbon dioxide, oxygen, water vapor, or a combination or sub-combinationthereof) into a surrounding environment. In embodiments where an opencircuit device is used, the amount exhaled by the one or more workerswithin an enclosure 1626 may be quite small with respect to the oversize of the enclosure 1626. Accordingly, the release of oxygen, watervapor, or the like into the interior of the enclosure 1626 may besufficiently small as to be negligible or at least within acceptablelimits (e.g., within the capacity of a gas management system 1632 torectify).

Referring to FIG. 17 , in selected embodiments, a manufacturing facilitymay comprise multiple work areas 1724 connected by one or more interfacemechanisms 1728 to form a network 1740. One or more of the work areas1724 forming such a network 1740 may be contained within enclosures1726. One or more of the work areas 1724 forming such a network 1740 maynot need an enclosure 1726 and, therefore, may not be contained withinone. One or more of the work areas 1724 forming such a network 1740 maybe contained within one or more buildings. For example, in selectedembodiments, all of the various work areas 1724 forming a network 1740may be contained within a single building. In such embodiments, any workareas 1724 contained within enclosures 1726 may be work areas 1724 thatrequire more environmental conditioning than that provided by thebuilding.

The various work areas 1724 of a network 1740 may be defined and/orarranged to correspond to certain manufacturing-related processes. Suchprocesses may include creating parts via additive manufacture; removalof parts from the machines that created them; removal of unamalgamatedgranular material; separating parts from a base or bed, one or moresupport structures (e.g., exterior portions of one or more travelingwalls that extend through a part, one or more temporary structuresprinted to support a part during additive manufacture that will not beincluded within the finished part, etc.), or the like; heat treating;peening; powder coating, painting, anodizing, or the like; packaging forshipment; or the like or a combination or sub-combination thereof.

For example, in selected embodiments, a network 1740 may include a firstwork area 1724 a for powder-bed fusion in an inert environment providedby an enclosure 1726, a second work area 1724 b for removing granularmaterial 144 from a build platform 146 in an enclosure 1726, a thirdwork area 1724 c for shot peening to improve surface finish in anenclosure 1726, a fourth work area 1724 d for heat treating to annealmetal parts in an enclosure 1726, a fifth work area 1724 e for removingparts from the build platform 146 in an enclosure 1726, a sixth workarea 1724 f for packing and shipping, or the like or a combination orsub-combination thereof.

In a first work area 1724 a, one or more machines may be containedwithin an enclosure 1726. The machines may all be the same size or ofvarying sizes. Similarly, the one or more machines may all be the sametype or of varying types. For example, in selected embodiments, each ofthe one or more machines within an enclosure 1726 may amalgamate (e.g.,unite, bond, fuse, sinter, melt, or the like) a particular granularmaterial in a batch process. In other embodiments, each of the one ormore machines within an enclosure may amalgamate a particular granularmaterial in a continuous process. In still other embodiments, one ormore machines within an enclosure may amalgamate a particular granularmaterial in a batch process, while one or more other machines within theenclosure may amalgamate the particular granular material in acontinuous process.

One or more machines of a first work area 1724 a may be arranged so thatsufficient space around the machines is preserved for one or more humanworkers, robots, or the like to access the machines, remove partstherefrom, vacuum up unamalgamated granular material for reuse, or thelike. Alternatively, or in addition thereto, a first work area 1724 amay include various gantries, catwalks, or the like that enable one ormore human workers, robots, or the like to access the machines (e.g.,visually access, physical access) from above. This may be helpful when afirst work area 1724 a includes one or more large machines where accessfrom the edges or sides thereof may be insufficient for certain tasks.

In a second work area 1724 b, unamalgamated granular material may beremoved from a build platform through various methods. For example, avacuum mechanism having a collection port that is controlled (e.g.,moved) manually or robotically may be used to collect unamalgamatedgranular material from around a part, off a build platform or bed or thelike. Alternatively, or in addition thereto, one or more flows ofpressurized gas that are controlled (e.g., aimed) manually orrobotically may be used to dislodge the unamalgamated granular materialfrom certain crevices, sweep the unamalgamated granular material off abuild platform or bed, and/or move the unamalgamated granular materialto one or more locations where it can be accessed by a vacuum.

In selected embodiments, first and second work areas 1724 a, 1724 b maybe contained within separate enclosures 1726 as illustrated. In otherembodiments, first and second work areas 1724 a, 1724 b may be containedwithin the same enclosure 1726. Moreover, in certain embodiments, firstand second work areas 1724 a, 1724 b may geographically overlap to atleast some degree, but may be temporally spaced in time (e.g., one ormore tasks corresponding to one work area 1724 a may be performed at adifferent time than one or more tasks corresponding to the other workarea 1724 b).

Alternatively, first and second work areas 1724 a, 1724 b may begeographically adjacent one another, but may temporally overlap to somedegree (e.g., one or more tasks corresponding to one work area 1724 amay be performed at the same time as one or more tasks corresponding tothe other work area 1724 b). In such embodiments, a first zone of amachine may correspond to or be a first work area 1724 a and a secondzone (or a combination of the second and third zones) may correspond toor be a second work area 1724 b.

In a third work area 1724 c, a peening process may be manually orrobotically applied to one or more parts. For example, in selectedembodiments, a manual or robotic system may use the same granularmaterial (i.e., the same granular material used to create the parts) asa shot media in a peening process to improve a surface finish of theparts. In a fourth work area 1724 d, an enclosure 1726 may be orcomprise an oven for heat treating one or more parts. Such an enclosure1726 may, therefore, be configured to generate, retain, and controlsignificant amounts of heat. The exact amount of heat may vary betweenthe size of the enclosure 1726, the nature of the parts being heattreated, and the like.

In a fifth work area 1724 e, one or more build platforms or beds may beseparated from the parts they supported, one or more exterior portionsof one or more traveling walls that extend through parts may be removed,one or more temporary structures printed to support parts duringadditive manufacture that will not be included within the finished partsmay be removed, or the like or a combination thereof. In selectedembodiments, this may involve wire electrical discharge machining (EDM)process. In such embodiments, parts may be submerged within a bath ofpartially de-ionized water where the ion content is carefully controlledas part of the EDM process. An enclosure for a fifth work area 1724 emay be included or omitted as desired or necessary.

In a sixth work area 1724 f, one or more parts may be prepared forshipping and/or shipped. For example, in a sixth work area 1724 f, oneor more parts may be painted, packaged, wrapped with plastic, secured toone or more pallets, or the like and loaded on a truck for shipment. Anenclosure for a sixth work area 1724 f may be included or omitted asdesired or necessary.

In selected embodiments, a network 1740 may comprise a plurality of workareas 1724 connected in series by one or more interface mechanisms 1728.Such interface mechanisms 1728 may enable one or more parts to flowsmoothly and efficiently from one work area 1724 to the next.Accordingly, the work areas 1724 may be arranged in the network 1740 sothat the tasks associated therewith may be performed in the required ordesired order.

Any of the described enclosures may maintain concentrations of inert orsubstantially inert gas (e.g., vacuum, nitrogen, argon, carbon-dioxide,or the like or a combination or sub-combination thereof) above a desiredlevel (e.g., argon at or above about 99.9% by volume). Alternatively, orin addition thereto, an enclosure may maintain concentrations of oxygenand/or water vapor below atmospheric levels (e.g., below 0.05% by volumefor gaseous oxygen, below 0.05% by volume for water vapor).

Vehicles can be used transport print beds, parts, or other materials viainterface mechanisms 1728 by rolling or otherwise moving over a path(e.g., a concrete floor), conveyor system, rail, or combination ofmultiple rails using traditional railroad concepts, linear movement on atrack using an encoder, linear motion provided by a pulley system,motion and/or levitation provided by magnetic levitation rails, motionvia a conveyor system or belt, or the like or a combination orsub-combination thereof. Large parts weighing 2,000 kilograms or morecan be transported. A vehicle may have wheels that roll on a supportingsurface. A support surface may be a floor (e.g., a floor having avisually, electronically, or magnetically detectable path appliedthereto or embedded therewithin). A support surface may also be one ormore rails. Such rails may be located below a part being carried by avehicle. Alternatively, such rails may be located above a part beingcarried by a vehicle. That is, the rails may be overhead rails and avehicle may be carriage or trolley rolling on the overhead rails whilesuspending a part therebelow.

Wheeled or other vehicles can be controlled and/or operated manually,automatically, autonomously, or semi-autonomously. For example, inselected embodiments, one or more wheeled vehicles may be pushed and/orsteered by one or more human operators. In other embodiments, variouson-board or off-board control systems may sense what is happening withrespect to a vehicle and instruct the vehicle when to move, when tostop, how to steer, and the like.

Many modifications and other embodiments of the invention will come tothe mind of one skilled in the art having the benefit of the teachingspresented in the foregoing descriptions and the associated drawings.Therefore, it is understood that the invention is not to be limited tothe specific embodiments disclosed, and that modifications andembodiments are intended to be included within the scope of the appendedclaims. It is also understood that other embodiments of this inventionmay be practiced in the absence of an element/step not specificallydisclosed herein.

The invention claimed is:
 1. An additive manufacturing method,comprising: providing an energy beam; positioning an opticallyaddressable light patterning device to receive the energy beam and emitlight as two-dimensional patterned beam, with the optically addressablelight patterning device rejecting energy not required to form thetwo-dimensional patterned beam; relaying the two-dimensional patternedbeam and focusing it as a two-dimensional image on a powder bed in anarticle processing device; and reusing rejected energy with a rejectedenergy handling device by either or both: recycling the rejected energyusing beam shaping optics; and directing the rejected energy to anarticle processing device to cause heating or further patterning of thea powdered material on the powder bed.
 2. The additive manufacturingmethod of claim 1, further comprising: providing a powdered material;providing an energy source that can produce an energy beam; directingthe energy beam from the energy source toward an energy beam patterningdevice to form a two-dimensional patterned energy beam; directing thetwo-dimensional patterned energy beam against the powder material toform a part having a manipulation point; and moving the part using amanipulator device to engage the manipulation point.
 3. The additivemanufacturing method of claim 1, further comprising: restricting, by anenclosure, an exchange of gaseous matter between an interior of theenclosure and an exterior of the enclosure; identifying a plurality ofmachines located within the enclosure; executing, by each machine of theplurality of machines, an independent process of additive manufacturecomprising directing a patterned energy beam at a powder bed; andmaintaining, by a gas management system during the executing, gaseousoxygen within the enclosure below atmospheric level.
 4. The additivemanufacturing method of claim 1, further comprising: creating, by afirst machine contained within a first enclosure, a first part via afirst process comprising additive manufacture using a patterned energybeam, wherein the first part has a weight greater than or equal to 2000kilograms; maintaining, by a first gas management system during thecreating, gaseous oxygen within the first enclosure below atmosphericlevels; transporting the first part from inside the first enclosure,through an airlock as the airlock operates to buffer between a gaseousenvironment within the first enclosure and a gaseous environment outsidethe first enclosure, and to a location exterior to both the firstenclosure and the airlock; and continuously supporting the weight of thefirst part during the transporting.